434 research outputs found

    Interacting galaxies and cosmological parameters

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    We propose a (physical)-geometrical method to measure the present rates of the density cosmological parameters for a Friedmann-Lemaitre universe. The distribution of linear separations between two interacting galaxies,when both of them undergo a first massive starburst, is used as a standard of length. Statistical properties of the linear separations of such pairs of ``interactivated'' galaxies are estimated from the data in the Two Degree Field Galaxy Redshift Survey. Synthetic samples of interactivated pairs are generated with random orientations and a likely distribution of redshifts. The resolution of the inverse problem provides the probability densities of the retrieved cosmological parameters. The accuracies that can be achieved by that method on matter and cosmological constant densities parameters are computed depending on the size of ongoing real samples. Observational prospects are investigated as the foreseeable surface densities on the sky and magnitudes of those objects.Comment: 8 pages, 6 figure

    Potential Application Of Radionuclide Scaling Factors To High Level Waste Characterization

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    Production sources, radiological properties, relative solubilities in waste, and laboratory analysis techniques for the forty-five radionuclides identified in Hanford�s Waste Treatment and Immobilization Plant (WTP) Feed Acceptance Data Quality Objectives (DQO) document are addressed in this report. Based on Savannah River Site (SRS) experience and waste characteristics, thirteen of the radionuclides are judged to be candidates for potential scaling in High Level Waste (HLW) based on the concentrations of other radionuclides as determined through laboratory measurements. The thirteen radionuclides conducive to potential scaling are: Ni-59, Zr-93, Nb-93m, Cd-113m, Sn-121m, Sn-126, Cs-135, Sm-151, Ra-226, Ra-228, Ac-227, Pa-231, and Th-229. The ability to scale radionuclides is useful from two primary perspectives: 1) it provides a means of checking the radionuclide concentrations that have been determined by laboratory analysis; and 2) it provides a means of estimating radionuclide concentrations in the absence of a laboratory analysis technique or when a complex laboratory analysis technique fails. Along with the rationale for identifying and applying the potential scaling factors, this report also provides examples of using the scaling factors to estimate concentrations of radionuclides in current SRS waste and into the future. Also included in the report are examples of independent laboratory analysis techniques that can be used to check results of key radionuclide analyses. Effective utilization of radionuclide scaling factors requires understanding of the applicable production sources and the chemistry of the waste. As such, the potential scaling approaches identified in this report should be assessed from the perspective of the Hanford waste before reaching a decision regarding WTP applicability

    Le trièdre ptérygo-clivien: reconstruction en 3D, stabilité ou variations possibles au cours de la croissance

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    The growth’s study, from skull’s radiographics, needs the use of superposition’s structures. Three X ray radiographics pictures from the front, from profile and from under are retalling by a soft. This orthogonazilation’s step has been realized for every child at two different ages. The reconstruction of the «clivus» straight and «pterygoïde» straights from three views gives the « pterygo-clivus triedre» which stability is studied for time.L’étude de la croissance, à partir de télécrânes, nécessite l’emploi de structures de superposition. Trois clichés radiographiques rayons X de face, de profil, en incidence axiale, ont été orthogonalisés par un logiciel. Cette étape a été réalisée pour chaque enfant à deux âges différents. La reconstruction de la droite clivienne et des droites ptérygoïdiennes sur les trois vues forme le trièdre ptérygo-clivien dont nous étudions la stabilité dans le temps

    Méthode d'orthogonalisation de clichés radio X par traitement d'images autorisant la reconstruction 3D d'éléments de la tête

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    In order to known better the unrolling of the growth, we dispode several radiographies elements which is sometimes difficult to connect with themselves.Using the computer, may give us the solution to this problem. We describe here a soft which authorizes the 3D reconstruction dating from X-ray radiographic pictures. During step called orthogonalization, the three pictures from the front, from profile and from under, are retalling by the soft. When it’s realized, any visible point from two views will automatically be visible in the third view.Pour mieux connaître le déroulement de la croissance, nous pouvons disposer de plusieurs éléments radiographiques qu’il est parfois difficile de relier entre eux.La réponse à ce problème peut être apportée par l’utilisation de moyens informatiques. Nous décrivons ici un logiciel qui autorise la reconstruction en 3D à partir de clichés radiographiques rayons X. Les trois clichés de face, de profil, et de dessous sont recadrés par le logiciel dans une étape dite «d’orthogonalisation». Une fois celle-ci réalisée, n’importe quel point visible sur deux vues sera automatiquement visible sur la troisième

    Tank 12H Acidic Chemical Cleaning Sample Analysis And Material Balance

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    A process of Bulk Oxalic Acid (BOA) chemical cleaning was performed for Tank 12H during June and July of 2013 to remove all or a portion of the approximately 4400 gallon sludge heel. Three strikes of oxalic acid (nominally 4 wt % or 2 wt %) were used at 55 �C and tank volumes of 96- to 140-thousand gallons. This report details the sample analysis of a scrape sample taken prior to BOA cleaning and dip samples taken during BOA cleaning. It also documents a rudimentary material balance for the Tank 12H cleaning results

    Structure of the poly-C9 component of the complement membrane attack complex

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    The membrane attack complex (MAC)/perforin-like protein complement component 9 (C9) is the major component of the MAC, a multi-protein complex that forms pores in the membrane of target pathogens. In contrast to homologous proteins such as perforin and the cholesterol-dependent cytolysins (CDCs), all of which require the membrane for oligomerisation, C9 assembles directly onto the nascent MAC from solution. However, the molecular mechanism of MAC assembly remains to be understood. Here we present the 8 Å cryo-EM structure of a soluble form of the poly-C9 component of the MAC. These data reveal a 22-fold symmetrical arrangement of C9 molecules that yield an 88-strand pore-forming β-barrel. The N-terminal thrombospondin-1 (TSP1) domain forms an unexpectedly extensive part of the oligomerisation interface, thus likely facilitating solution-based assembly. These TSP1 interactions may also explain how additional C9 subunits can be recruited to the growing MAC subsequent to membrane insertion

    Conformational changes during pore formation by the perforin-related protein pleurotolysin

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    Membrane attack complex/perforin-like (MACPF) proteins comprise the largest superfamily of pore-forming proteins, playing crucial roles in immunity and pathogenesis. Soluble monomers assemble into large transmembrane pores via conformational transitions that remain to be structurally and mechanistically characterised. Here we present an 11 Å resolution cryo-electron microscopy (cryo-EM) structure of the two-part, fungal toxin Pleurotolysin (Ply), together with crystal structures of both components (the lipid binding PlyA protein and the pore-forming MACPF component PlyB). These data reveal a 13-fold pore 80 Å in diameter and 100 Å in height, with each subunit comprised of a PlyB molecule atop a membrane bound dimer of PlyA. The resolution of the EM map, together with biophysical and computational experiments, allowed confident assignment of subdomains in a MACPF pore assembly. The major conformational changes in PlyB are a ~70° opening of the bent and distorted central β-sheet of the MACPF domain, accompanied by extrusion and refolding of two α-helical regions into transmembrane β-hairpins (TMH1 and TMH2). We determined the structures of three different disulphide bond-trapped prepore intermediates. Analysis of these data by molecular modelling and flexible fitting allows us to generate a potential trajectory of β-sheet unbending. The results suggest that MACPF conformational change is triggered through disruption of the interface between a conserved helix-turn-helix motif and the top of TMH2. Following their release we propose that the transmembrane regions assemble into β-hairpins via top down zippering of backbone hydrogen bonds to form the membrane-inserted β-barrel. The intermediate structures of the MACPF domain during refolding into the β-barrel pore establish a structural paradigm for the transition from soluble monomer to pore, which may be conserved across the whole superfamily. The TMH2 region is critical for the release of both TMH clusters, suggesting why this region is targeted by endogenous inhibitors of MACPF function

    Sustainable food security in India—Domestic production and macronutrient availability

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    <div><p>India has been perceived as a development enigma: Recent rates of economic growth have not been matched by similar rates in health and nutritional improvements. To meet the second Sustainable Development Goal (SDG2) of achieving zero hunger by 2030, India faces a substantial challenge in meeting basic nutritional needs in addition to addressing population, environmental and dietary pressures. Here we have mapped—for the first time—the Indian food system from crop production to household-level availability across three key macronutrients categories of ‘calories’, ‘digestible protein’ and ‘fat’. To better understand the potential of reduced food chain losses and improved crop yields to close future food deficits, scenario analysis was conducted to 2030 and 2050. Under India’s current self-sufficiency model, our analysis indicates severe shortfalls in availability of all macronutrients across a large proportion (>60%) of the Indian population. The extent of projected shortfalls continues to grow such that, even in ambitious waste reduction and yield scenarios, enhanced domestic production alone will be inadequate in closing the nutrition supply gap. We suggest that to meet SDG2 India will need to take a combined approach of optimising domestic production and increasing its participation in global trade.</p></div

    The principles of communicative language use

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    The paper aims to overview some typical principles of communicative language use in a cognitive pragmatic approach applying a reductionist method in order to demonstrate that the well-known principles can be reduced to a very general rationality (economy) principle. After briefly reviewing the principles the paper re-evaluates them and provides a new classification of them relying on the definition of ostensive-inferential communication. The principles which can be divided into rationality and interpersonality principles are really principles of effective information transmission on objects and selves. They refer to two kinds of language use: informative and communicative ones. The only principles valid for only communicative language use are the communicative principle of relevance and the principle of communicative intention suggested in the present article. Finally, the paper reduces all rationality and interpersonality principles to a very general rationality principle, i.e., the cognitive principle of relevance
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